In a conventional color printer, four photosensitive drums each corresponding to one of four colors of yellow, magenta, cyan and black are juxtaposed. Four developing cartridges are provided each for one of the photosensitive drums. Each developing cartridge includes a developing roller for supplying toner to the corresponding photosensitive drum.
For forming a colored image, an electrostatic latent image is formed on each photosensitive drum. The electrostatic latent image is then developed into a visible toner image when toner is supplied thereto from the corresponding developing roller. The toner image is then transferred onto a sheet, which is conveyed by a conveyer belt, either directly or indirectly via an intermediate transfer belt, thereby forming a black-and-white image or a colored image on the sheet.
The toner transferred from the photosensitive drum is deposited on the conveyor belt. A cleaning member is therefore provided for collecting toner from the conveyor belt. The toner collected (removed) from the conveyor belt is conveyed to and stored in a waste toner accommodating unit.
There has been proposed a developing cartridge that is integrally formed with a waste toner accommodating unit. Under this construction, when toner within the developing cartridge is used up and the developing cartridge is replaced with a new developing cartridge, the waste toner accommodating unit is also replaced with a new one that is integrated with the new developing cartridge.